1. Field of the Invention
The present invention generally relates to a method for operating a substrate processing apparatus.
2. Description of the Background Art
Piezoelectric elements, developed and currently put into practical use in a sensor, an actuator, a transmitter, an RF filter or the like and Ferroelectric Random Access Memory (FeRAM), used as a nonvolatile memory in various types of IC cards, hand-held terminals or the like, both have a structure in which a ferroelectric thin film is sandwiched by precious metal electrodes.
For microfabrication of the ferroelectric thin films and precious metal electrodes, a dry etching method with the use of a plasma is used, but ferroelectric thin films and precious metal electrodes are regarded as difficult etching materials and are poor in reactivity with halogen gas (plasma). Since these halogenated substances have low vapor pressures, it is likely that etched products are not exhausted as gas but adhere to the inner wall of a chamber.
When ions in the plasma are brought into contact with such adherent substances, they may react with each other, causing the adherent substances to be peeled off from the inner wall of the chamber to generate particles. Such generated particles adhere onto a substrate to be processed and have reduced device yield.
See, Japanese Patent Document JP-A 8-269445.